Judging Similarity

24 Pages Posted: 17 Mar 2014 Last revised: 23 Jan 2015

See all articles by Shyamkrishna Balganesh

Shyamkrishna Balganesh

Columbia University - Law School

Irina D. Manta

Hofstra University - Maurice A. Deane School of Law

Tess Wilkinson‐Ryan

University of Pennsylvania Carey Law School

Date Written: 2014


Copyright law’s requirement of substantial similarity requires a court to satisfy itself that a defendant’s copying, even when shown to exist as a factual matter, is quantitatively and qualitatively enough to render it actionable as infringement. By the time a jury reaches the question of substantial similarity, however, the court has usually heard and analyzed a good deal of evidence: about the plaintiff, the defendant, the creativity involved, the process through which the work was created, the reasons for which the work was produced, the defendant’s own creative efforts and behavior, and on occasion the market effects of the defendant’s copying. Despite having this large body of evidence before it, the jury is required to answer the question of substantial similarity through a mere comparison of the two works. In this Essay, we report results from a series of experiments in which subjects were presented with a pair of images and asked to assess the similarity between the two works using the criteria ordinarily given to fact-finders for the substantial similarity determination. When provided with additional information about the simple fact of copying, or about the amount of creative effort that went into the protected work, we saw an appreciable variation (i.e., upwards) in subjects’ assessments of similarity between the works, suggesting that fact-finders are sensitive to additional information about the two works and the creators who produced them, contrary to what current law assumes. Our study suggests that the availability and salience of such additional information actively distorts fact-finders' assessments of the similarity between the two works, calling into question the purported objectivity of the substantial similarity requirement as a whole.

Keywords: substantial similarity, copyright infringement, cognitive bias

JEL Classification: O34

Suggested Citation

Balganesh, Shyamkrishna and Manta, Irina D. and Wilkinson-Ryan, Tess, Judging Similarity (2014). 100 Iowa Law Review 267 (2014), U of Penn Law School, Public Law Research Paper No. 14-15, Hofstra Univ. Legal Studies Research Paper No. 2014-09, Available at SSRN: https://ssrn.com/abstract=2409811

Shyamkrishna Balganesh (Contact Author)

Columbia University - Law School ( email )

435 West 116th Street
New York, NY 10025
United States

HOME PAGE: http://www.law.columbia.edu/faculty/shyamkrishna-balganesh

Irina D. Manta

Hofstra University - Maurice A. Deane School of Law ( email )

121 Hofstra University
Hempstead, NY 11549
United States

Tess Wilkinson-Ryan

University of Pennsylvania Carey Law School ( email )

3501 Sansom Street
Philadelphia, PA 19104
United States

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